Religion is a completely different thing from the claim that the Earth is six thousand years old. That's just crazy.

It is my mission to change the world. I'm not kidding: Make no small plans, dream mighty things. I feel if we get enough people engaged in climate change, we will get enough people to change the world. We will revolutionize the way we produce electricity and provide clean water to people.

If you look back on all the teachers that you liked, I am sure you will find they were very entertaining.

Science is the key to our future, and if you don’t believe in science, then you’re holding everybody back. And it’s fine if you as an adult want to run around pretending or claiming that you don’t believe in evolution, but if we educate a generation of people who don’t believe in science, that’s a recipe for disaster. We talk about the Internet. That comes from science. Weather forecasting. That comes from science. The main idea in all of biology is evolution. To not teach it to our young people is wrong.

As my old professor Carl Sagan said so often, 'When you’re in love, you want to tell the world.’ And I base my beliefs on the information and the process that we call science. It fills me with joy to make discoveries every day of things I’ve never seen before. It fills me with joy to know that we can pursue these answers. It is an astonishing thing that we are — you and I are one of the ways the universe knows itself.

Recommending or insisting on abstinence has been completely ineffective.

There really is no such thing as race. We all came from Africa. We are all of the same stardust. We are all going to live and die on the same planet, a Pale Blue Dot in the vastness of space. We have to work together.